Air ballasted accumulator



Sept. 1, '1942. R. .'J. FEUCHTER AIR BALLASTED ACCUMULATOR FiledDec. 30, 4 1939 3 Sheets-Sheet l u From /aam/a Sept 1, 1942 R.v J. FELICI-ITER AIR BALLASTED ACCUMULATOR Sheets-Shet 2 Filed Dec. 50, 1939 Patented Sept. l, 1942 AIR BALLASTED ACCUMULATOR Robert J. Feuchter, Chicago, Ill., assignor to Charles F. Elmes Engineering Works, Chicago, Ill., a corporation of Illinois Application December 30, 1939, Serial No. 311,894

4 Claims.

The present invention relates to air ballasted accumulators of the general type described in the prior application of Robert J. Feuchter, Serial No. 295,154, filed September 15, 1939. Accumulators of this type are used in the operation of hydraulic presses and other machines Where it is necessary to supply a volume of liquid under pressure.

The principal purpose of the present invention is to provide an accumulator of the character described, together with suitable means Whereby the pressure of the hydraulic liquid supplied to the consuming machine, such as a hydraulic press, may be held within a definite range of pressure dependent upon the preliminary setting, whether such pressure is a relatively low pressure or is a pressure approaching the maximum available pressure from the accumulator. In other words, the present device is designed and equipped to provide a single air ballasted accumulator which, when once charged, is capable of use as a source of reserve liquid under pressure for al Wide range of pressure demands, without change in the air ballast in the accumulator.

It is a further purpose of the present invention to provide a control system for air ballasted accumulators of the character described Wherein the safety features of avoiding excessive withdrawal of liquid so as to get air into the press lines, and avoiding dangerous high pressures are provided and, in addition, the accumulator may be quickly shifted from low pressure service to high pressure service.

The features and advantages of the present invention will appear more fully as the description proceeds, reference being had to the accompanying drawings wherein a preferred form of the invention is shown. It is to be understood, however, that the drawings and description are illustrative only, and are not to be taken as limiting the invention except insofar as it is limited by the claims.

In the drawings,

Fig, 1 is a somewhat diagrammatic view illustrating the accumulator and the necessary connections for operating the same;

Fig. 2 is a diagrammatic view of the electrical connections necessary for controlling the equipment, and

Figs. 3 and 4 are diagrammatic views with suitable legends to illustrate the operations of the accumulator at different ranges of pressure.

Referring now in detail to the drawings, the present invention illustrates an air ballasted accumulator vessel Ill which is of the general character described in the application above referred to. This accumulator is adapted to be charged with air and partially filled with hydraulic liquid. The vessel I0 has, at the top thereof, a high pressure air safety valve II which is set to open and exhaust the air pressure from the accumulator at a pressure well above the highest operating pressure, and well below the pressure at which the vessel would be liable to rupture. The liquid inlet to the vessel IU is shown at I2. A valve I3 is provided in the pipe I2 so that the liquid inlet may be shut off manually at this point. A drain pipe I4 having a valve I5 is provided for draining the vessel whenever desired. For the purpose of observing and controlling the liquid level and pressure within the vessel I, a control pipe I6 connects the bottom and top of the vessel I0. This pipe I6 is connected to the control apparatus hereinafter described.

The control apparatus comprises means for connecting a source of liquid under pressure, such as one or more pumps, not shown, to the pipe I2 through a safety closing valve I'I and a pipe I8. The control apparatus is adapted to actuate the safety closing valve I1 to permit withdrawal of liquid from the vessel I0 when the demand of the pressure operated machine is heavy, and to supply liquid under pressure to the vessel I0 when the demand is light or is cut off. The control apparatus is adjustable to maintain the desired liquid level and pressure in the 'accumulator vessel. The control apparatus also controls a liquid supply valve I9 which is adapted to bypass the liquid from the pumps whenever the pressure in the vessel I0 exceeds certain predetermined values.

The operation of the control apparatus is by means of certain pressure and liquid level responsive electrical switches and utilizes the usual shop air supply for the actual control operations An air compressor may be used in the intial charging of the accumulator vessel. Such compressor, when used, is adapted to be connected to the pipe I6 through a branch pipe 20 having a valve 2I therein. It is obvious, of course, that the usual shop air pressure can be connected to the pipe 20 to initially ll the accumulator vessel with air under pressure equal to the shop pressure.

The safety closing valve I1 is adapted to be operated by means of air pressure supplied through a pipe 22 to a diaphragm unit 23 so that the valve I'I may be closed to prevent withdrawal of liquid from the accumulator vessel at certain times. However, the construction of the valve is such that even when it is closed to prevent such withdrawal, it permits liquid to flow into said accumulator vessel when the pressure in the pipe I8 exceeds the pressure within the accumulator vessel so that the pressure within the Vessel may be built up. The construction of the diaphragm unit 23 and the safety closing valve I1 is the same as that illustrated in the prior application above referred to. A solenoid operated valve 24 controls the supply of air to the pipe 22 from a pipe 25 that is connected to the shop air supply line 26.

The valve I9, which controls the supply of liquid from the pressure pump, is also adapted to be actuated by air pressure applied to a control device 21 which is similar to that shown in the prior application. Air is supplied to the device 21 through a pipe 28 that is controlled by a solenoid operated valve 29. The valve 29 receives air from a branch pipe 36 that is connected to the shop air supply line 26. lThe operation of the device 21 is as follows: When air is supplied to the device 21 through the pipe 23, the valve I9 is adapted to connect a pump supply pipe 3l to a distributor pipe 32 that leads to the pipe I8 and the safety closing valve I1 and to the presses or other machinery requiring the liquid under pressure. When the air pressure is withdrawn from the device 21, then the valve I9 is adapted l to be moved to connect the supply pipe 3| to a by-pass pipe 33, which returns the liquid to a tank supplied for the pump. The pump and the tank are not shown herein, since they are wellknown in the art and form no part of the present invention.

A manometer 34 of the type disclosed in the application above referred to is connected to the vessel I6 by means of two pipes 35 and 36. The pipe 35 connects to the pipe I6 through a valve 31, while the pipe 36 connects to the pipe I6 through a valve 38. Suitable test outlets 39, 46, 4I, 42 and 43 are provided at various levels in the pipe I6. A condenser 44 is provided at the top of the pipe 36. The manometer 34 is electrically connected to the solenoid operated valves 24 and 29 so as to control the high and low liquid level independently of the pressure in the accumulator vessel I 6. The top level is so adjusted that if the normal liquid level reaches the connection for the pipe 36 to the pipe I6, the electrical circuit is actuated to cause moving of the valve 29 into exhaust position by deenergizing the solenoid which actuates it. This will release air from the pipe 28 and cause the pump control valve I9 to move to bypass position. The

lower level index is set so that upon withdrawal of the amount of liquid necessary to drop the liquid level in the vessel to below the point where the pipe 35 connects to the pipe I6, the electrical connections for the manometer will open the circuit for the solenoid controlling the valve 24, This will exhaust the air pressure from the diaphragm of the safety closing valve I1 and thereby close this valve to prevent further withdrawal of the liquid from the vessel I6.

The normal operation by which the pressure is controlled in the vessel I 0 is by means of two pressure responsive governors 45 and 46. These governors are connected to the vessel I6 by a common pipe 41. The governor 45 controls the actuation of the valve 24, while the governor 46 controls the actuation of the valve 29. These pressure governors are of the type manufactured by the General Electric Company and sold under catalogue number CR2922-E. The governor 45 is adapted to close the energizing circuit for the valve 24 at a predetermined pressure in the vessel I6 and open the circuit at a lower pressure in said vessel. The governor 46, on the other hand, is adapted to close the energizing circuit for the valve 29 at a predetermined pressure in the vessel I6 and to open the circuit at a higher pressure. In the event that current fails in both energizing circuits for the valves 24 and 29, the valves move to exhaust position. This causes the safety closing valve I1 to close and causes the valve I 9 to move to pump bypass position, thereby preventing further supply of liquid to, or withdrawal of liquid from, the vessel I6.

Referring now to Fig. 2 of the drawings, and to the governors 45 and 46, the showing in this figure illustrates the electrical connections for the governors and the solenoid operated valves 24 and 29. Figure 2 also illustrates the electrical connections for the manometer 34, whereby it controls the valves 24 and 29.

In Fig. 2, current is supplied from a transformer 49 which is energized from a suitable source of current. One terminal of the secondary of the transformer 48 is connected to the governors 45 and 46 by a lead 49. The other side of the transformer is connected to the governors 45 and 46 by a lead 56. Two branch leads 5I and 5Ia connect the manometer to the leads 49 and 56. Two manometer controlled relays 52 and 53 are connected to the lead 49 by a lead 54. The other terminals of the relays 52' and 53 are connected by leads 55 and 56 respectively to control terminal contacts 51 and 58 of the manometer 34. The lead 56 is permanently connected to the movable contact 59 of the manometer. The lead 56 is connected by a branch lead 66 to two solenoids 6I and 62 which operate the valves 24 and 25. The solenoids 6I and 62 are connected respectively to normally closed contacts 63 and 64 of the relays 52 and 53 by leads 65 and 66. The relays 52 and 53 have armatures 61 and 68 respectively. The armature 61 is connected to the governor 45 by a lead 69. The armature 68 is connected to the governor 46 by a lead 16.

The governor 45 consists, essentially, of a Bourdon tube 1I to which a needle is geared for indicating pressure on a dial. A contact mechanism indicated diagrammatically at 12 is adjustably mounted to determine the pressures at which the governor will close and open the energizing circuit for the solenoid 6I of the valve 24. The minimum pressure drop necessary to open the energizing circuit is about ten per cent of the minimum pressure at which the governor operates. For example, a governor that will operate over a maximum range of 1000 lbs. to 4000 lbs. may be set to open the energizing circuit on a drop in pressure of 100 lbs. from any pressure between 1000 lbs. and 4000 lbs. for which it is set.

The Contact mechanism 12 controls a relay 13 which has a holding armature 14 and a solenoid controlling armature 15. If the pressure applied moved far enough by pressure drop to engage the right hand stationary contact, then a short circuit around the relay 13 is established, causing it to be deenergized. Armatures 14 and l5 then drop back.

When the armature 15 is attracted, it connects the lead 49 directly to the lead 69 and current is supplied over the leads 49, 59, and 65 to the solenoid 6I to move the valve 24 up and supply shop air to open the safety closing valve l1. When the armature 15 drops back, the circuit for the solenoid 6l is broken at the armature and the valve 24 drops to release air from the safety closing valve Il and let it close.

The governor 46 has a contact mechanism l5, a relay 11, a holding armature '18, and a solenoid controlling armature 19. The detailed construction and operation is the same as that of the governor 45. However, it will be noted that the armature '19 normally connects the lead 49 to the lead l0 so as to keep the solenoid 92 of the valve 29 energized. When the pressure rises sufficiently to bring the movable contact of the mechanism 'i6 against the left hand stationary contact thereof, the relay 'i1 is energized and armature 19 is attracted to break connection between the leads 49 and '10, thereby deenergizing the solenoid 62 of the valve 29 and allowing the valve 29 to drop This causes the valve I9 to bypass they pump supply.

When the pressure on the governor 46 falls enough to bring the movable contact of mechanism 16 against the right hand contact thereof, the relay 11 is deenergized to release its armature 19, and the armature 19 again connects the leads 49 and l0.

Referring now to Figs. 3 and 4, the manner in which the accumulator is used for two widely different ranges of pressure will be described. Initially, it is necessary to charge the accumulator with air up to a certain minimum pressure. The shop air supply is used to charge the vessel I0 up to the pressure of the shop air supply. Then the air is supplied by an air compressor. Liquid is pumped into the vessel until the level of the lower` test outlet 43 is reached. The air compressor is utilized to charge the vessel so that the pressure therein, when the liquid level is at the test outlet 43, is somewhat below the minimum operating pressure. In the present instance, the pressure is 1430 lbs., as indicated on Fig, 3. Further use of the air compressor is not necessary in charging the accumulator up to the desired working pressure. This is done much more rapidly by means of the liquid pump.

Assuming that the working pressure is to be about 1600 lbs., the pump bypass valve controlling governor 45 is set to energize its relay and open the circuit of the solenoid 62 of the valve 29 at 1650 lbs. In the example shown in Fig. 3, this means that when the pump is bypassed there is about 91 gallons of liquid in the vessel l0 and above it there is about 275 gallons of air at a pressure of 1650 lbs. An allowable drop of ten per cent in pressure will give about 28 gallons of liquid for operating the presses before the pressure drops to 1500 lbs.

The governor 45 for the safety closing valve l1 is set to open the safety closing valve for withdrawal of liquid from the vessel I0 when the pressure rises to 1600 lbs. As liquid is with-drawn when the presses are put into operation, the pump remains bypassed until the pressure in the vessel l0 drops to 1550 lbs. At this pointy the governor 46 energizes the solenoid of the valve 29 and the valve I9 is'moved to connect the pump to the line 32 leading to the presses and to the valve I l. Now both the accumulator and the pump feed the presses until the pressure drops to 1500 lbs. where the safety closing valve is closed against further withdrawal of liquid from the vessel l0. This closing is controlled by the governor 45 which breaks the circuit for the solenoid 6I when the pressure in the vessel reaches 1500 lbs.

Thus it will be seen that by setting the governors 45 and 46 so that the pump is cut in at a predetermined pressure of 1550 lbs. and bypassed again at a higher pressure of 1650 lbs. while the vessel I0 is cut in at 1600 lbs.` by the opening of the valve il, and cut off the line at 1500 lbs. by the closing of the valve l1, the range of 1500 lbs. to 1650 lbs. is available for operation of the presses with the combined pump capacity and the available 28 gallons of accumulator capacity.

To make the accumulator available for higher pressure operation, it is necessary to re-set the governors 45 and 46 for the higher pressure range and to utilize the pump to add more liquid to the vessel I0` and thus compress the air therein. In Fig` 4, the conditions of higher pressure operation are given. At this higher level of pressure, however, since the air volume in the vessel I0 is much less, the liquid available from the accumulator to the presses is only 12 gallons for a ten per cent drop in pressure.

By simply adjusting the pressure controlled governors 45 and 46 in accordance with the foregoing explanation, it is possible to operate the accumulator at any pressure Within the range of its high and low limits. The practical high limit is reached when the volume of air becomes too small to supply sufficient liquid over the permissible variation in the pressure supplied. The practical low limit is above the pressure at which the liquid level falls so low as to actuate the manometer control to close the safety valve I1.

From the foregoing description it is believed that the nature of the present invention will be readily apparent to those skilled in this art. Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An air ballasted accumulator system of the character described, comprising a vessel charged with gas and a liquid, a control valve normally operable to a position to prevent withdrawal of liquid from said vessel, a second control valve operable to direct liquid under pressure to said vessel through said first named valve whenever the pressure supplied by said second Valve exceeds the pressure in the vessel, suitable conduits connecting sai-d valves, Vessel and source, control means for said valves comprising means responsive to pressure change in said vessel to positively open said first named valve when the pressure in said vessel reaches a predetermined value and permitting said valve to close at a predetermined substantially lower value, means responsive to pressure change in said vessel to close said second named valve when the pressure in said vessel exceeds the pressure at which the first named valve is opened, by a predetermined amount, and to open said second named valve when the pressure in said vessel drops a predetermined amount from the pressure at which the said second valve is closed, said two last named means having mechanism for varying the range of vessel pressures over which they are elective, and safety control means independent of said pressure responsive means for permitting closing of said first named valve when the liquid level in said vessel falls below a predetermined limit.

2. An air ballasted accumulator system of the character described, comprising a vessel charged with gas and a liquid, a control valve normally Aoperable to a position to prevent withdrawal of liquid from said vessel, a second control valve operable to direct liquid under pressure to said vessel through said rst named valve Whenever the pressure supplied by said second valve exceeds the pressure in the vessel, suitable conduits connecting said valves, Vessel and source, control means for said valves comprising means responsive to pressure change in said vessel to positively open said rst named valve when the pressure in said vessel reaches a predetermined value and permitting said valve to close at a predetermined substantially lower value, means responsive to pressure change in said vessel to close said second named valve when the pressure in said vessel exceeds the pressure at which the rst named valve is opened, by a predetermined amount, and to open said second named valve when the pressure in said vessel drops a predetermined amount from the pressure at which the said second valve is closed, and safety control means independent of said pressure responsive means for permitting closing of said first named valve when the liquid level in said vessel falls below a predetermined limit.

3. An air ballasted accumulator system of the character described, comprising a vessel charged with gas and a liquid, a control Valve normally operable to a position to prevent Withdrawal of liquid from said vessel, a second control valve operable to direct liquid under pressure to said vessel through said first named valve whenever the pressure supplied by said second valve exceeds the pressure in the vessel, suitable conduits connecting said valves, vessel and source, control means for said valves comprising means responsive to pressure change in said vessel to positively open said rst named valve when the pressure in said vessel reaches a predetermined value and permitting said valve to close at a predetermined substantially lower value, means responsive to pressure change in said vessel to close said second named valve when the pressure in said vessel exceeds the pressure at which the first named valve is opened, by a predetermined amount, and to open said second named valve when the pressure in said vessel drops a predetermined amount from the pressure at which the said second Valve is closed, said two last named means having mechanism for varying the range of vessel pressures over which they are effective, and safety control means independent of said pressure responsive means for closing said second named valve when the liquid level in said vessel exceeds a predetermined limit.

4. An air ballasted accumulator system of the character described, comprising a vessel charged with gas and a liquid, a control valve normally operable to a position to prevent Withdrawal of liquid from said vessel, a second control valve operable to direct liquid under pressure to said vessel through said first named valve whenever the pressure supplied by said second valve exceeds the pressure in the vessel, suitable conduits connecting said valves, vessel and source, control means for said valves comprising means responsive to pressure change in said vessel to positively open said first named valve when the pressure in said vessel peaches a predetermined value and permitting said valve to close at a predetermined substantially lower Value, means responsive to pressure change in said vessel to close said second named valve when the pressure in said Vessel exceeds the pressure at which the first named valve is opened, by a predetermined amount, and `to open said second named valve when the pressure in said vessel drops a predetermined amount from the pressure at which the said second valve is closed, and safety control means independent of said pressure responsive means for closing said second named valve when the liquid level in said vessel exceeds a predetermined limit.

ROBERT J FEUCHTER. 

